Thirty-five millimeter cameras have been in existence for a number of years and have become very popular in the industry. Usually, the film for such camera is packaged into a cassette or cartridge and has a leader extending therefrom. In most such cameras, the camera has a door which extends across the rear of the camera to cover a film-receiving chamber and is opened to insert the film cartridge into the chamber which receives the cartridge and leader which are inserted into the chamber in a direction transverse to the plane of the film. In such cameras, the user manually inserts the end of the film leader into a slot of a take-up spool in the chamber which is readily visible because the entire length of the spool is visible to the user. The film has perforations on at least one edge thereof and the take-up spool has a projection that catches with a film perforation when the take-up spool is rotated manually or automatically.
There has been proposed a 35 mm still camera which incorporates a feature which is referred to as a "drop-in" film loading feature. This type of camera has a cartridge-receiving cavity and a film leader-receiving channel joining said cavity. The cavity and channel are adapted to receive the cartridge and film leader which are dropped into the same in the direction of the film plane. This cavity and channel extend from one face or edge of the camera housing into the film chamber area which defines the desired film path. The leader end-receiving slot of the take-up spool in such a drop-in loader camera is difficult to see since the cavity therefore is small and only the spool end is fully exposed. However, this slot must still be initially manually aligned with the end of the portion of the leader-receiving channel in the film path, so that the leader end will drop into the take-up spool slot. Such necessity for manually aligning the slot of the take-up spool is inconvenient, and the user can readily forget to do so, in which event the initiation of a film winding operation will not take place when the take-up spool is rotated.
A drop-in loading camera is particularly useful in a half-frame 35 mm camera where the picture frames are one half the size of a full 35 mm frame. In such case, the full frame is split transversely to the length of a full frame so that the half frame has about the same proportions of length to width in a direction across rather than along the length of the film as does a full 35 mm frame. In such case, if the drop-in film loading side of the camera is the vertical side of the camera, rather than the rear or top thereof, the film extends and is advanced vertically rather than horizontally past the imaging area. The long dimension of a half frame picture is then horizontal when the camera is held in a normal manner to obtain a similar frame orientation for a full frame 35 mm camera. The half frame drop-in loading type camera described, which provides twice the number of pictures than a full frame 35 mm camera, is the type of camera to which the present invention is applied in the exemplary form of the invention to be described, although the invention is also applicable to drop-in loaded full size 35 mm cameras.
Some of the newer types of still cameras have motor-driven take-up and cartridge spools forming what is referred to as "reverse film transport systems". In these types of cameras, as soon as a film chamber door is closed, the motor-driven film transport system is started to drive the take-up spool to pre-wind and transport the entire film, except the rear end portion thereof locked to the supply spool in the film cartridge. However, as previously indicated, such a pre-wind operation will not take place if the user does not insert the leader end into the leader end-receiving slot in the take-up spool. The pre-wound camera is then automatically set to a rewind and reverse film transport mode, and as an exposure is taken, one frame of film is rewound into the cartridge so that there is no possibility of ruining the already-exposed part of the film upon accidental opening of the film chamber door.